Crystalline poly(aryl ether ketone)s (PAEK) with high heat resistance and chemical resistance are highly desirable for the manufacture of molded articles for demanding automotive, aerospace, electronics and oil field applications. Poly(aryl ether ketone)s are important engineering resins because of their generally excellent properties such as good mechanical properties at elevated temperatures, exceptional chemical resistance against organic solvents and strong acids and bases, low wear rate, abrasion and fire resistance, and electrical insulating.
However, the relatively low glass transition temperatures (Tg) of these crystalline PAEK resins limit their use at high temperatures under load. This deficiency has been improved, but not solved, by the addition of reinforcement fillers such as, fiberglass, carbon fibers and ceramic or mineral fillers. Unfortunately, while reinforcement improves stiffness and strength, the compound still displays similar performance in long-term load performance. That is, the creep resistance and relaxation under stress still perform as if the material is un-reinforced. The addition of reinforcing fibers also increases weight, reduces flow and induces anisotropy in molded parts. Such anisotropy in a part may, for example, result in warp or other undesirable dimensional changes, such as curling in a film. In some instances the fiber additives can interfere with the surface smoothness of the shaped parts, causing uneven surface properties. This is especially true with respect to thin parts and films. The addition of reinforcing filler to PAEK resins will also make it difficult to extrude thin films and fibers. This is the main reason that the Tg is the dominant factor for engineering polymer applications. The ability to increase Tg through the use of blends is, therefore, a very valuable option.
Furthermore, the elongation to break is reduced significantly and processing characteristics are also adversely affected. Elongation to break or ductility is a critical requirement in many industrial applications requiring sealing and impact resistance.
Thus there exists a need for crystalline PAEK formulations with a range of improved properties, for instance load-bearing capabilities at high temperature, while maintaining good ductility and melt processability, thereby allowing for their improved use in molded articles, tubes, sheets, films and fibers.